Power interchange that transfers electric power from one location to another location is required to adjust an electric power supply and demand balance. Patent literature 1 discloses classifying each power-receiving facility into a plurality of groups under a condition such as a power consumption pattern and interchanging a margin electric power among the groups.
When power interchange is performed, a power loss occurs due to a resistance in a power transmission line or AC/DC conversion, for example. While it is possible to reduce the loss to some extent by performing high-voltage power transmission or improving power conversion efficiency, it is difficult to completely eliminate the loss. When a demand side requests a certain amount of electric power, a supply side needs to provide electric power in consideration of the power that will be lost.